Liquid coolant supply system

ABSTRACT

A liquid coolant supply system for supplying a liquid coolant to a thermal therapy catheter includes a sensor control unit, a liquid coolant containment unit and mounts. The sensor control unit includes a pump, a cooling device, a temperature sensor and a pressure sensor. The liquid coolant containment unit includes a sealed reservoir, a coolant-sensor interface module and a pump interface fluidly coupled to the thermal therapy catheter. The coolant-sensor interface module includes a body defining a fluid chamber, a temperature interface supported adjacent the fluid chamber within the body, and a pressure interface supported adjacent the fluid chamber within the body. The mounts removably support the sealed reservoir, pump interface, temperature interface and pressure interface of the containment unit adjacent the cooling device, the pump, the temperature sensor and the pressure sensor. The temperature interface communicates a temperature indicant of the liquid coolant circulating through the fluid chamber to the temperature sensor. The pressure interface communicates a pressure indicant of the liquid coolant circulating through the fluid chamber to the pressure sensor. The cooling device and the pump are controlled based upon the sensed temperature and pressure of the liquid coolant.

BACKGROUND OF THE INVENTION

The present invention relates to field of microwave thermal therapy oftissue. In particular, the present invention relates to a coolant-sensorinterface module for enabling temperature and pressure of a liquidcoolant within a thermal therapy catheter fluid supply system to besensed.

Benign prostatic hyperplasia (BPH) may be treated using transurethralthermal therapy as described in further detail in U.S. Pat. No.5,413,588 entitled DEVICE FOR ASYMMETRICAL THERMAL THERAPY WITH HELICALDIPOLE MICROWAVE ANTENNA and in U.S. patent application Ser. No.08/309,137 entitled COOLANT PRE-CHILLING PRIOR TO BENIGN PROSTATICHYPERPLASIA TREATMENT, both assigned to Urologix, Inc., which are hereinincorporated by reference. During transurethral thermal therapy,tumorous tissue growth within the prostate surrounding the urethra isheated to necrose the tumorous tissue to treat BPH. Transurethralthermal therapy is administered by use of a microwave antenna-containingcatheter which includes a multi-lumen shaft. Energization of themicrowave antenna causes the antenna to emit electromagnetic energywhich heats tissue within the prostate. To avoid unnecessary andundesirous damage to the urethral and adjacent healthy tissues, thecatheter is provided with cooling lumens through which liquid coolantcirculates to control the temperature distribution of tissue surroundingthe catheter.

Typically, the liquid coolant is supplied to the thermal therapycatheter by a pump which pumps the liquid coolant from a reservoirthrough the thermal therapy catheter. Conventional liquid coolant supplysystems comprise relatively large reservoirs containing as much as fivegallons of liquid coolant from which liquid coolant is supplied to thethermal therapy catheter. The liquid coolant contained within the largereservoir is simply maintained at room temperature. Although the liquidcoolant being circulated through the thermal therapy catheterexperiences a temperature increase during thermal therapy, suchincreases are relatively insignificant due to the large volume of liquidcontained in the reservoir. However, conventional liquid coolant supplysystems have failed to provide for precise, closed loop control of thetemperature and pressure of the liquid coolant being supplied to thethermal therapy catheter. In addition, conventional liquid coolantsupply systems are expensive and require extensive and time consumingsterilization between a treatment of different patients.

SUMMARY OF THE INVENTION

A coolant-sensor interface module for enabling pressure temperature andpressure of a liquid coolant within a thermal therapy catheter fluidsupply system to be sensed by a temperature sensor and a pressuresensor, respectively includes a body, a temperature interface and apressure interface. The body defines a fluid chamber with an inlet portand an outlet port for allowing the liquid coolant to circulate throughthe fluid chamber. The temperature interface is supported adjacent thefluid chamber within the body and communicates a temperature indicant ofthe liquid coolant circulating through the fluid chamber to thetemperature sensor. The pressure interface is supported adjacent thefluid chamber within the body and communicates a pressure indicant ofthe liquid coolant circulating through the fluid chamber to the pressuresensor.

The coolant-sensor interface module of the present invention ispreferably incorporated as part of a liquid coolant containment unitwhich additionally includes a liquid coupling assembly for fluidlyconnecting the coolant-sensor interface module to inlet and outlet portsof the thermal therapy catheter and for containing the liquid coolant asthe liquid coolant is cooled and pumped by cooling and pumping means.Preferably, the liquid coupling assembly includes a sealed reservoir anda pump interface fluidly connected to one another. In the preferredembodiment of the present invention, the sealed reservoir comprises athin thermally conducting bag having a plurality of winding channels forchanneling liquid flow adjacent the cooling means. The pump interfacepreferably comprises a compressible liquid conduit that is dynamicallycompressed so that liquid coolant may be circulated with a peristalticpump.

Lastly, the liquid cooling containment unit incorporating thecoolant-sensor interface is preferably utilized as part of a liquidcoolant supply system which includes a sensor control unit having apump, a cooling device, a temperature sensor and a pressure sensor. Inthe preferred embodiment, the cooling device comprises a flat thermallyconducting plate which is temperature controlled based upon temperaturesensed by the temperature sensor. The pump of the sensor control unitpreferably comprises a peristaltic pump which pumps and circulates theliquid coolant at a flow rate based upon pressure sensed by the pressuresensor. In the preferred embodiment in which the temperature interfaceis illustrated as a radiation emitter which emits radiation based uponthe temperature of the liquid coolant and in which the pressureinterface is illustrated as being a flexible diaphragm which expandsbased upon the pressure of the liquid coolant, the temperature sensorand the pressure sensor of the sensor control unit comprise an infraredradiation sensor and at least one pressure transducer, respectively. Toenable the liquid coolant containment unit of the present invention tobe easily mounted and removed from the sensor control unit, the sensorcontrol unit includes mounts for removably supporting the reservoiradjacent the cooling plate, the pump interface adjacent the peristalticpump, and the temperature interface and pressure interface of the sensorinterface module adjacent the temperature sensor and pressure sensor ofthe sensor control unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view of a male pelvic region showing theurinary organs effected by benign prostatic hyperplasia.

FIG. 2A is a side view of the distal end of the urethral catheter.

FIG. 2B is an enlarged sectional view of the proximal end of theurethral catheter.

FIG. 3 is a cross-sectional view of the urethral catheter of FIG. 2Btaken along line 3--3.

FIG. 4 is a perspective view of a proximal region of the urethralcatheter with the end portion taken in section from line 4--4 of FIG.2B.

FIG. 5 is an enlarged view of the male pelvic region of FIG. 1 showingthe urethral catheter positioned within the prostate region.

FIG. 6 is a partially exploded perspective view of a cooling system ofthe present invention.

FIG. 7 is a greatly enlarged side elevational view of a liquidcontainment unit of the cooling system.

FIG. 8 is a fragmentary side elevational view of the liquid containmentunit including a sensor interface module.

FIG. 9 is a cross-sectional view of the sensor interface module takenalong line 9--9.

FIG. 10 is a side elevational view of liquid coolant supply systemillustrating the liquid coolant containment unit supported adjacent to asensor control unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a vertical sectional view of a male pelvic region showing theeffect benign prostatic hyperplasia (BPH) has on the urinary organs.Urethra 10 is a duct leading from bladder 12, through prostate 14 andout orifice of penis end 18. Benign tumorous tissue growth withinprostate 14 around urethra 10 causes constriction 20 of urethra 10,which interrupts the flow of urine from bladder 12 to orifice 16. Thetumorous tissue of prostate 14 which encroaches urethra 10 and causesconstriction 20 can be effectively removed by heating and necrosing theencroaching tumorous tissue. Ideally, with the present invention, onlyperiurethral tumorous tissue of prostate 14 anterior and lateral tourethra 10 is heated and necrosed to avoid unnecessary and undesirousdamage to urethra 10 and to adjacent healthy tissues, such asejaculatory duct 24 and rectum 26. A selective heating of benigntumorous tissue of prostate 14 (transurethral thermal therapy) is madepossible by microwave antenna-containing catheter 28 of the presentinvention, which is shown in FIGS. 2A and 2B.

FIG. 2A shows a side view of a distal end of catheter 28. FIG. 2B showsan enlarged sectional view of a proximal end of catheter 28. As shown inFIGS. 2A and 2B, catheter 28 generally includes multi-port manifold 30,multi-lumen shaft 32, shaft position retention balloon 34, connectionmanifold 35, cooling system 36, microwave generating source 38 andurethral thermometry unit 39.

Multi-port manifold 30 includes inflation port 40, urine drainage port42, microwave antenna port 44, cooling fluid in port 46 and coolingfluid out port 48. Ports 40-48 communicate with corresponding lumenswithin shaft 32. Manifold 30 is preferably made of medical-gradesilicone sold by Dow Corning under the trademark Silastic Q-7-4850.

Multi-lumen shaft 32 is connected to manifold 30 at shaft distal end 50.Shaft 32 is a multi-lumen, Foley-type urethral catheter shaft which isextruded from a flexible, medical-grade silicone sold by Dow Corningunder the trademark Silastic Q-7-4850. Shaft 32, which has an outerdiameter of about 16 French, includes outer surface 52, which isgenerally elliptical in cross-section as shown in FIG. 3. Shaft 32 islong enough to permit insertion of proximal shaft end 54 through urethra10 and into bladder 12. In one preferred embodiment, shaft 32 is coatedwith a hydrophilic solution sold by Hydromer, Inc. under the markHydromer, which lubricates outer surface 52 of shaft 32 and facilitatesits advancement within urethra 10.

As shown in FIG. 2B-4, shaft 32 includes temperature sensing lumen 56,microwave antenna lumen 58, urine drainage lumen 60, balloon inflationlumen 62, cooling fluid intake lumens 64A and 64B, and cooling fluidexhaust lumens 66A and 66B. Lumens 56-66B generally extend from distalshaft end 50 to proximal shaft end 54.

Temperature sensing lumen 56 is positioned near first side 68 of shaft32. Temperature sensing lumen 56 communicates with microwave antennaport 44 and permits insertion of thermometry sensor 69 within shaft 32to monitor the temperature of surrounding tissue when shaft 32 isinserted within urethra 10. Sensor 69 exits through port 44 and isconnected through connection manifold 35 to urethral thermometry unit39. Urethral thermometry unit 39 measures urethral temperature basedupon signals from temperature sensor 69 within catheter 28. In apreferred embodiment, thermometry sensor 69 is a fiber opticluminescence type temperature sensor sold by Luxtron Corporation.Temperature sensing lumen 56 is sealed at proximal end 54 by siliconeplug 70.

Microwave antenna lumen 58 is eccentric to the longitudinal axis ofshaft 32, antenna lumen 58 being positioned nearer first side 68 ofshaft 32 than second side 72 of shaft 32. Antenna lumen 58 is sealed atproximal end 54 by silicone plug 70A. At its distal end, antenna lumen58 communicates with microwave antenna port 44. Microwave antenna 74 ispermanently positioned within antenna lumen 58 near balloon 34. Antenna74 is positioned within antenna lumen 58 so as to be generally situatedadjacent the benign tumorous tissue of prostate 14 when shaft 32 isproperly positioned within urethra 10. As shown in FIGS. 2A-2B, antenna74 is bonded within antenna lumen 58 by adhesive bond 75. Antenna 74 iscarried at the proximal-most end of coaxial cable 76. The distal-mostend of coaxial cable 76 is connected to connection manifold 35 by aconventional quick-coupling fitting 73. Coaxial cable 76 communicateswith microwave generating source 38 by connection cable 76A, which isconnected between microwave generating source 38 and connection manifold35. In one embodiment, connection cable 76A is a standard RG 400 coaxialcable. Microwave generating source 38 produces a maximum of 100 watts ofelectrical power at about 915 MHz frequency, ±13 MHz, which is withinthe FCC-ISM standards. When antenna 74 is energized by microwavegenerating source 38, antenna 74 emits electromagnetic energy whichcauses heating of tissue within prostate 14.

Urine drainage lumen 60 is positioned adjacent antenna lumen 58, betweenantenna lumen 58 and second side 72. Urine drainage lumen 60communicates with urine drainage port 42 and defines a drainage path forurine when proximal end 54 of shaft 32 is inserted within bladder 12.Urine drainage lumen 60 is connected to urine drainage lumen extension78 at proximal end 54. Urine drainage lumen extension 78 is bondedwithin proximal end cap 80. End cap 80 is further bonded over outersurface 52 of shaft 32 at proximal shaft end 54, with cavity 82surrounding lumen extension 78. With end cap 80 and urine drainage lumenextension 78 in place, opening 84 to lumen extension 78 permits urine todrain from bladder 12 through urine drainage tureen 60 and out urinedrainage port 42 when proximal shaft end 54 is inserted within bladder12. Drainage of urine from bladder 12 is necessary due to frequentbladder spasms which occur during transurethral thermal therapy.

Balloon inflation lumen 62 is positioned near second side 72, generallybetween urine drainage lumen 60 and second side 72. Balloon inflationlumen 62 communicates with inflation port 40 and is sealed at proximalend 54 by silicone plug 70B. Balloon inflation lumen 62 communicateswith interior 86 of balloon 34 by opening 88.

Balloon 34, which is formed from a tubular section of a flexible,medical-grade silicone sold by Dow Coming under the trademark SilasticQ-7-4720, is secured over shaft 32 by bonding balloon waists 90 and 92over exterior surface 52 of shaft 32 near proximal shaft end 54. Balloon34 is inflated by an inflation device (not shown), which is connected toinflation port 40 and which supplies positive fluid pressure to interior86 of balloon 34. Balloon 34 is deflated when the inflation devicesupplies a negative fluid pressure (i.e., a vacuum) to interior 86 ofballoon 34. Balloon 34 serves to retain shaft 32 in a fixed positionwithin urethra 10 when balloon 34 is inflated within bladder 12 nearbladder neck 22, as shown in FIG. 5.

As shown in FIG. 2B, FIG. 3 and FIG. 4, cooling fluid intake lumens 64A,64B are positioned circumjacent first side 68, between first side 68 andantenna lumen 58. Cooling fluid intake lumens 64A, 64B extend fromdistal shaft end 50 to proximal shaft end 54 where lumens 64A, 64B areexposed to cavity 82 of end cap 80. Intake lumens 64A, 64B arerelatively narrow in cross-section and have a relatively smallcross-sectional surface area. Water contained within intake lumens 64A,64B performs two essential functions. First, water contained withinlumens 64A, 64B absorbs some of the microwave energy emitted by antenna74. This assists, in part, in controlling the volume of tissue adjacentfirst side 68 of shaft 32 that is heated above about 45° C. Second, thewater within lumens 64A, 64B absorbs heat energy generated by themicrowave energy from adjacent tissues (i.e., urethra 10) via thermalconduction. This prevents the portion of urethra 10 adjacent first side68 from being overheated and damaged when antenna 74 is energized.

Cooling fluid exhaust lumens 66A, 66B are circumjacent second side 72with lumens 66A, 66B generally positioned between second side 72 andantenna lumen 58. Like intake lumens 64A, 64B, exhaust lumens 66A, 66Bextend from shaft distal end 50 to shaft proximal end 54 where exhaustlumens 66A, 66B are exposed to cavity 82 of end cap 80. Exhaust lumens66A, 66B are wider in cross-section than intake lumens 64A, 64B, andhave a cross-sectional area greater than the cross-sectional area ofintake lumens 64A, 64B. Water within exhaust lumens 66A, 66B istherefore capable of absorbing a greater amount of microwave energy whenantenna 74 is energized. As a result, for a given power output frommicrowave generating source 38, the temperature of tissue adjacentsecond side 72 will remain below about 45° C. Water within exhaustlumens 66A, 66B also absorbs heat energy from adjacent tissue (i.e.,urethra 10) when antenna 74 is energized, which prevents the portion ofurethra 10 adjacent second side 72 from being overheated and damagedwhen antenna 74 is energized.

Intake lumens 64A, 64B and exhaust lumens 66A, 66B are supplied withdeionized water from cooling system 36. Water from cooling system 36 ischilled and maintained at a temperature of between about 12°-25° C.,preferably 12°-15° C., and pumped at a rate of between about 100-150milliliters per minute via water feed line 94A to connection manifold35. The water flows through connection manifold 35 to water feed line94B and to water intake port 46, which communicates with water intakelumens 64A, 64B. Under fluid pressure, the water circulates throughintake lumens 64A, 64B to cavity 82 of end cap 80. The water returns tocooling system 36 through exhaust tureens 66A, 66B to fluid exhaust port48. The water is carried from water exhaust port 48 via water returnline 96B to connection manifold 35, and from connection manifold 35 tocooling system 36 via water return line 96A. The water is thenre-chilled and re-circulated. Water feed line 94B and water return line96B are each provided with a conventional quick-coupling fitting 65A and65B, respectively, which permits catheter 28 to be easily disconnectedfrom cooling system 36.

FIG. 6 is a partially exploded perspective view of cooling system 36.Cooling system 36 generally includes liquid coolant containment unit 100and sensor control unit 102. Liquid coolant containment unit 100contains the liquid coolant supplied to catheter 28 by cooling system 36and generally includes coolant-sensor interface module 104 and liquidcoupling assembly 106. Sensor interface module 104 temporarily receivesand contains circulating liquid coolant and interfaces between thecirculating liquid coolant and sensor control unit 102. Sensor interfacemodule 104 physically isolates the circulating liquid coolant fromsensor control unit 102, but enables sensor control unit 102 to senseand detect temperature and flow rate of the liquid coolant circulatingthrough sensor interface module 104. In particular, sensor interfacemodule 104 permits sensor control unit 102 to sense the temperature andthe pressure, a parameter corresponding to flow rate, of the liquidcoolant circulating through sensor interface module 104. As a result,sensor interface module 104 prevents the circulating liquid coolant fromphysically contacting sensor control unit 102 while permitting thetemperature and flow rate of the circulating fluid to be sensed so thattime consuming and expensive cleaning and sterilization of sensorcontrol unit 102 between patients may be eliminated. In addition, sensorinterface module 104 permits liquid coolant containment unit 106 to beinexpensively manufactured and renders liquid cooling containment unit106 disposable, thereby eliminating otherwise necessary cleaning andsterilization of a non-disposable, fixed liquid coolant containmentunits.

Liquid coupling assembly 106 fluidly connects sensor interface module104 to water feed line 94B and water return line 96B of thermotherapycatheter 28 (shown in FIG. 2B). In particular, liquid coupling assembly106 circulates the liquid coolant from water return line 96B into sensorinterface module 104 and circulates the liquid coolant from sensorinterface module 104 into water feed line 94B of catheter 28. Liquidcoupling assembly 106 contains the liquid coolant as the temperature ofthe liquid coolant is maintained at a desired temperature and pumped bysensor control unit 102. Liquid coupling assembly 106 includes waterreturn line 96A, reservoir 110, pump interface tube 112 and water feedline 94A. Water return line 96A fluidly connects reservoir 110 of liquidcoolant containment unit 106 to water return line 96B of catheter 28.Reservoir 110 is fluidly connected between water return line 96A andpump interface tube 112. Reservoir 110 preferably has an enlarged flowpassage or flow area with respect to water return line 96a to reduce theflow rate of the liquid coolant through reservoir 110. Reservoir 110includes mounting holes 116 for releasably mounting reservoir 110 tosensor control unit 102 so that reservoir 110 may be removed from sensorcontrol unit 102 to permit easy replacement of liquid containment 100.

Pump interface tube 112 fluidly connects reservoir 110 and sensorinterface module 104. Pump interface tube 112 channels liquid coolantfrom reservoir 110 into sensor interface module 104. In addition, pumpinterface tube 112 interfaces with sensor control unit 102 to allowsensor control unit 102 to pump liquid coolant through pump interfacetube 112 and to circulate the liquid coolant through liquid coolantcontainment unit 100. Lastly, water return line 94A carries the liquidcoolant from sensor interface module 104 to water return line 94b ofcatheter 28.

Sensor control unit 102 simultaneously performs multiple functions andincludes cooling plate 120, mounts 122, pump 124, mounts 126,temperature sensor 128 and pressure sensor 130. Cooling plate 120 is agenerally flat plate of material having a high degree of thermalconductivity, preferably aluminum. The temperature at the surface ofcooling plate 120 is regulated by circulating temperature regulatedfluid behind and adjacent to the surface of cooling plate 120.Alternatively, the temperature at the surface of cooling plate 120 maybe regulated with other well-known conventional heating and coolingmeans such as refrigeration coils, resistors or the like. Cooling plate120 cools, as necessary, the liquid coolant circulating through liquidcoupling assembly 106. In particular, cooling plate 120 regulates thetemperature of the liquid coolant circulating through reservoir 110 byindirect thermal conduction. Because cooling plate 120 does not directlycontact the liquid coolant to regulate the temperature of the liquidcoolant, sensor control unit 102 remains free from potentialcontamination concerns and the health risks.

Mounts 122 preferably comprise pins which project sensor control unit102. Mounts 122 engage mounting openings 116 of reservoir 110 toremovably support reservoir 110 adjacent to and in contact with coolingplate 120. As a result, cooling plate 120 is in sufficient contact withreservoir 110 to efficiently regulate the temperature of the liquidcoolant circulating through reservoir 110. At the same time, mounts 122permit reservoir 110 of liquid containment unit 106 to be easily removedand separated from cooling plate 120 of sensor control unit 102. As canbe appreciated, mounts 122 may alternatively comprise any one of avariety of releasable mounting mechanisms such as hook and loopfasteners.

Pump 124 preferably comprises a peristaltic pump including rotatingroller pins 134 and jaw 136. As is conventionally known, roller pins 134rotate at a controllable speed. Jaw 132 clamps over and adjacent toroller pins 134 to hold and position a flexible fluid containmentstructure adjacent the rotating roller pins 134. In the preferredembodiment illustrated, pump interface tube 112 comprises a flexibletube which is positioned between roller pins 134 and jaw 136. Jaw 136 ispositioned so as to clamp or hold pump interface tube 112 against rollerpins 134. Roller pins 134 at least partially compress the flexiblematerial forming the tube of pump interface tube 112. Rotation of rollerpins 134 about a common axis dynamically compresses the flexiblematerial forming the tube of pump interface tube 112 to pump andcirculate fluid through and along pump interface tube 112. As a result,pump 124 draws the liquid coolant through water return line 96A andreservoir 110 by creating a vacuum within pump interface tube 112 andsimultaneously pumps fluid from pump interface tube 112 into sensorinterface module 104 and through water feed line 94A to catheter 28.

Mounts 126 preferably comprise pins which project from sensor controlunit 102. Mounts 126 engage mounting detents 108 to removably andreleasably support sensor interface module 104 adjacent to temperaturesensor 128 and pressure sensor 130. As can be appreciated, mounts 126may alternatively comprise any one of a variety of releasable mountingmechanisms such as hook and loop.

Temperature sensor 128 preferably comprises a conventional infraredsensor sized to match a corresponding radiation emitter of sensorinterface module 104. Temperature sensor 128 senses radiation emittedfrom the radiation emitter of sensor interface module 104 to determine acorresponding temperature of the liquid coolant circulating throughsensor interface module 104. Because temperature sensor 128 sensestemperature by sensing or detecting radiation emitted by the radiationemitter of sensor interface module 104, temperature sensor 128 is ableto determine the temperature of the liquid coolant circulating throughsensor interface module 104 indirectly without directly contacting theliquid coolant. Thus, the need for cleaning and possibly sterilizingtemperature sensor 128 between patients is reduced or eliminated.

Pressure sensor 130 comprises a conventionally known pressuretransducer. Pressure sensor 130 senses pressure of the liquid coolantcirculating through sensor interface module 104. Because pressure is aparameter corresponding to flow rate, pressure sensor 130 enables sensorcontrol unit 102 to determine the flow rate of the liquid coolantthrough sensor interface module 104. In addition, pressure sensor 130also enables sensor control unit 102 to determine the flow rate of theliquid coolant through liquid containment unit 100 and through catheter128. Because pressure sensor 130 indirectly senses pressure and the flowrate of the liquid coolant circulating through sensor interface module104, temperature sensor 130 avoids contamination and health concernswhich otherwise result from direct contact between the sensors and theliquid coolant.

Cover 132 is movably coupled to sensor control unit 102 adjacent coolingplate 120, pump 124, temperature sensor 128 and pressure sensor 130.Cover 132 is a generally flat solid plate which is movable in an openedposition and a closed position. In the opened position, cover 132 allowsreservoir 110 to be positioned adjacent to cooling plate 120, pumpinterface tube 112 to be positioned within pump 124, and sensorinterface module 104 to be positioned adjacent to temperature sensor 128and pressure sensor 130. At the same time, in the opened position, cover132 also allows liquid containment unit 100 to be removed and separatedfrom sensor control unit 102 for replacement of liquid containment unit100. In the closed position, cover 132 positions and maintains reservoir110 adjacent cooling plate 120, pump interface tube 112 within pump 124and sensor interface module 104 adjacent temperature sensor 128 andpressure sensor 130. In the preferred embodiment, cover 132 includes aninsulating member 134 made of a thermally insulating material such asStyrofoam. Member 134 is positioned and supported by cover 132 so as toengage reservoir 110 of liquid containment unit 100. In addition tosandwiching reservoir 110 of liquid containment unit 100 betweeninsulating member 134 and cooling plate 120, insulating member 134insulates the liquid coolant circulating through reservoir 110 fromambient air to allow greater temperature control of the liquid coolantcirculating through liquid containment unit 100.

FIG. 7 is a greatly enlarged side elevational view of liquid containmentunit 100 illustrating reservoir 110 and pump interface tube 112 ingreater detail. As best shown by FIG. 7, reservoir 110 preferablycomprises a sealed flexible bag including surface walls 140, end walls142, partitions 144, flaps 146, inlet port 148, outlet port 150 andmembrane 151. Surface walls 140 are preferably formed from a relativelythin, thermally conductive material such as polyurethane. Surface walls140, end walls 142 and partitions 144 define a plurality of windingchannels 152 which extend from inlet port 148 to outlet port 150.Channels 152 define a flow passage having an area larger than thecross-sectional area of water return line 96A. As a result, the flowrate of liquid coolant circulating through winding flow passages 152 ofreservoir 110 is greatly reduced as it enters reservoir 110. Windingchannels 152 cause the circulating liquid coolant to flow back and forthacross the adjacent cooling plate 120 (shown in FIG. 6) to ensure thatthe liquid coolant circulates proximate to cooling plate 120 for asufficient amount of time for allowing cooling plate 120 to adjust thetemperature of the liquid coolant while also allowing cooling plate 120and reservoir 110 to be compacted into a small area. Flaps 146 extendalong a perimeter of reservoir 110 and define mounting detents 116.

Membrane 151 extends through one of surface walls 140 and communicateswith winding channels 152. Membrane 151 is preferably formed from a gaspermeable material which blocks the flow of liquids. As a result,membrane 151 allows air and other gases trapped within liquidcontainment unit 100 to escape while preventing the escape of the liquidcoolant.

Reservoir 110 is preferably formed by heat sealing a pair of thinflexible sheets of plastic material such as polyurethane to one anotherto form seams along end walls 142 and partitions 144. Portions 154 and156 of the plastic sheets are preferably heat sealed to one anotherabout tubular insets 158, 159 to form inlet port 148 and outlet port150, respectively. Apertures are punched through flaps 146 to formmounting detents 116. Similarly, an aperture is punched through one ofthe sheets to form a window in which membrane 151 is heat sealed. Due toits simple design and manufacture, the preferred embodiment of reservoir110 is inexpensive and disposable. At the same time, reservoir 110provides a sealed aseptic containment unit which allows the temperatureof the liquid coolant circulating through reservoir 110 to be preciselyadjusted by thermal conduction from cooling plate 120.

As best shown by FIG. 7, pump interface tube 112 preferably comprises atube made of a flexible and compressible material such as poly vinylchloride (PVC). The ends of the tube forming pump interface tube 112 aresealed to inset 159 extending from outlet port 150 and sensor interfacemodule 104. Pump interface tube 112 preferably has a length sufficientfor extending over and around roller pins 134 of pump 124. The tube ofpump interface tube 112 preferably defines a lumen having a diameter ofsufficient size to enable pump 124 (shown in FIG. 2) to pump the liquidcoolant at a necessary flow rate through sensor interface module 104 andwater feed line 94A through catheter 28. As can be appreciated othercompressible interface structures, such as compressible bags, may beused in lieu of tube 112.

FIGS. 8 and 9 illustrate sensor interface module 104 in greater detail.FIG. 8 is a fragmentary side elevational view of liquid containment unit100 illustrating sensor interface module 104 in greater detail. FIG. 9is a cross-sectional view of sensor interface module 104 taken alonglines 9--9 of FIG. 8. As best shown by FIGS. 8 and 9, sensor interfacemodule 104 includes body 160, fitting 162, sealing bore 163, fill guide164, fill plug 166, temperature interface 168 and pressure interface170. Body 160 is a generally flat substantially rectangular structurewhich encircles and structurally supports temperature interface 168 andpressure interface 170 while defining a fluid chamber 172 adjacent totemperature interface 168 and pressure interface 170. Body 160 alsopreferably defines a pair of mounting detents 108 which stably andreleasably support temperature interface 168 and pressure interface 170adjacent temperature sensor 128 and pressure sensor 130 of sensorcontrol unit 102 (shown in FIG. 6). Body 160 is preferably integrallyformed and made from a translucent, rigid and lightweight material suchas polycarbonate. As can be appreciated, body 160 may have any one of avariety of shapes and configurations and be made from any one of avariety of materials which enable body 160 to support a pressureinterface between a fluid chamber and corresponding pressure andtemperature sensors of a sensor control unit.

As best shown by FIG. 8, fluid chamber 172 includes two relatively flat,thin circular cavities 174 and 176 in fluid communication with oneanother. Cavity 174 is located adjacent to temperature interface 168while cavity 176 is located adjacent to pressure interface 170. Cavity174 has a shape corresponding to the shape of temperature interface 160and is sized only slightly larger than the surface area of temperaturesensor 168. Similarly, cavity 176 has a shape corresponding to the shapeof pressure interface 170 and has an area only slightly larger than thesurface area of pressure interface 170. Cavity 172 channels and directsthe liquid coolant from pump interface tube 112 across pressureinterface 170 and temperature interface 174 into water feed line 94A. Atthe same time, chamber 172 temporarily retains the liquid coolant as thetemperature and pressure of the liquid coolant are sensed.

As further shown by FIGS. 8 and 9, housing 160 defines inlet port 180,outlet port 182 and fill port 184. Inlet port 180 extends through body106 and provides communication between the interior of pump interfacetube 112 and cavity 176. Outlet port 182 extends through body 160 andprovides fluid communication between cavity 174 and the interior ofwater feed line 94A. Together, inlet port 180 and outlet port 182 permitliquid coolant to circulate through cavity 172 of sensor interfacemodule 104. Fill port 184 extends through body 160 and providescommunication with fluid chamber 172 for permitting liquid containmentunit 100 to be filled and emptied with a supply of liquid coolant.

Sealing bore 163 and fitting 162 allow pump interface tube 112 and waterfeed line 94A to be coupled to body 160 in fluid communication withinlet 180 and outlet port 182, respectively. Fitting 162 preferablyintegrally projects from body 160 and is sized for mating with pumpinterface tube 112 to fluid connect pump interface tube 112 and inletport 180. Sealing bore 163 extends into body 160 adjacent to outlet port182. Sealing bore 163 receives water feed line 94A and allows water feedline 94A to sealingly mate with side walls of sealing bore 163 so as toprovide fluid communication between the interior of water feed line 94Aand outlet port 182.

Fill guide 164 is a generally rigid tubular member which defines a borein fluid communication with fill port 184. Fill guide 164 receives anozzle or another similar conventional fluid coupling of a fluid supply.For example, fill guide 164 preferably is sized for receiving a needleof a syringe through which fluid is supplied through fill port 184 intoliquid containment unit 100. Once liquid containment unit 100 isadequately supplied with liquid coolant, fill guide 164 receives fillplug 166 which seals and blocks fill port 184.

Temperature interface 168 transmits liquid coolant temperature indiciafrom the liquid coolant circulating through chamber 172 to temperaturesensor 128 (shown in FIG. 6). Temperature interface 168 allowstemperature sensor 128 to indirectly determine the temperature of theliquid coolant within sensor interface module 104. Preferably,temperature interface 168 comprises a black body radiation emitterformed from a black body radiation emitting material such as anodizedaluminum. Temperature interface 168 is fixed to and supported by body160 adjacent to chamber 172. As conventionally known, black bodies emitradiation based upon their temperature. Because the liquid coolantcirculating through chamber 172 contacts the black body radiationemitting material of temperature interface 168, the black body radiatingemitting material emits radiation which corresponds to the temperatureof the liquid coolant circulating through fluid chamber 172. Thus,temperature interface 168 allows the temperature of the liquid coolantto be indirectly sensed and measured.

Pressure interface 170 is fixed and supported by body 160 adjacent fluidchamber 172. Pressure interface 170 transmits pressure related indiciaof the liquid coolant within fluid chamber 172 across pressure interface170 to pressure sensor 130 (shown in FIG. 6) so that pressure sensor 130may indirectly sense and determine the pressure and corresponding flowrate of the liquid coolant through chamber 172. Pressure interface 170preferably comprises a flexible diaphragm made of polyurethane which issealed to body 160 adjacent chamber 172. The flexible diaphragm expandsand contracts based upon the pressure of the liquid coolant circulatingthrough fluid chamber 172. As a result, the flexible diaphragm ofpressure interface 170 allows pressure sensor 130 to sense the pressureexerted by the liquid coolant upon the flexible diaphragm to therebydetect the pressure of the liquid coolant circulating through chamber172.

FIG. 10 is a side elevational view of liquid coolant supply system 36illustrating liquid coolant containment unit 100 removably supportedadjacent to sensor control unit 102. For ease of illustration, portionsof cover 132 are omitted. As best shown by FIG. 10, during treatment ofBPH, temperature interface 168 and pressure interface 170 of sensorinterface module 104 are removably supported adjacent to, and preferablyin contact with, temperature sensor 128 and pressure sensor 130 ofsensor control unit 102, respectively by mounts 126. Reservoir 110 ofliquid coupling assembly 106 is removably supported adjacent to coolingplate 120 by mounts 122. Lastly, pump interface tube 112 is releasablyand removably clamped and supported against roller pins 134 by jaw 136of pump 124.

Once liquid coolant is supplied to liquid containment unit 100 andcatheter 28 (shown in FIG. 2A) through fill port 184, the liquid coolantis circulated through catheter 28 and liquid containment unit 100 byrotation of roller pins 134 about axis 190 in the clockwise directionindicated by arrow 192. As a result, the liquid coolant moves in thedirection indicated by arrow 193 through pump interface tube 112. Theliquid fluid continues to circulate into fluid chamber 172 adjacent topressure sensor 170 and temperature sensor 168 and through water feedline 94A to catheter 28 as indicated by arrow 194. After the liquidcoolant has circulated through catheter 28, the liquid coolant isreturned to liquid coolant supply system 100 through water return line96A. The returning liquid coolant continues to circulate throughchannels 152 within reservoir 110 adjacent to cooling plate 120 asindicated by arrows 195. As the liquid coolant circulates throughchannels 152 adjacent to cooling plate 120, the liquid coolant ischilled by thermal plate 120. Due to winding channels 152, the liquidcoolant flows adjacent to thermal plate 120 for a sufficient period oftime to sufficiently decrease or increase the temperature of the liquidcoolant as necessary. In addition, winding channels 152 also enablereservoir 110 and thermal plate 120 to be compact and thermallyefficient. Any gases trapped within liquid containment unit 106 arepermitted to escape through membrane 151 within reservoir 110.

Once the liquid coolant enters fluid chamber 172 of sensor interfacemodule 104, the liquid coolant accumulated within fluid chamber 172exerts a force against the diaphragm of pressure interface 170. Inresponse, the diaphragm expands against pressure sensor 130 (shown inFIG. 6). Pressure sensor 130 senses the pressure exerted upon it bydiaphragm 170 and determines the pressure of the liquid coolant withinfluid chamber 172 of sensor interface module 104. From a determinedpressure, the flow rate of the liquid coolant through sensor interfacemodule 104 and through liquid containment unit 106 may be determined bysensor control unit 102.

At essentially the same time, the liquid coolant temporarily containedwithin fluid chamber 172 thermally conducts or withdraws heat to or fromthe black body material forming temperature interface 168. Temperatureinterface 168 emits a corresponding radiation which is sensed by theinfrared radiation sensor of temperature sensor 128 (shown in FIG. 6).Sensor control unit 102 determines the temperature of the liquid coolantwithin sensor interface control module 104 based upon the sensed levelof radiation detected by temperature sensor 128.

Liquid coolant supply system 102 permits closed-loop control of thetemperature and pressure of the liquid coolant being pumped andcirculated through catheter 28. Thermal plate 120 adjusts thetemperature of the liquid coolant flowing through reservoir 110. Almostimmediately after leaving reservoir 110, the liquid cooling is pumped bypump 124 into sensor interface module 104. Sensor interface module 104allows sensor control unit 102 to indirectly sense and determine boththe pressure correlating to flow rate and the temperature of the liquidcoolant immediately before the liquid coolant is pumped through waterfeed line 94A into and through catheter 28. Temperature sensor 128 andpressure sensor 130 of sensor control unit 102 provide signals to sensorcontrol unit 102 which represent or correspond to the temperature andthe pressure (corresponding to flow rate) of the liquid coolant. Usingthe data representing the temperature and pressure of the liquid coolantwithin sensor interface module 104, sensor control unit 102 adjusts boththe temperature of thermal plate 120 and the rotational speed of rollerpins 134 about axis 190 to adjust both the temperature and the flow rateof the liquid coolant circulating through liquid containment unit 100.As a result of the closed-loop feedback between sensor interface module104 and sensor control unit 102, liquid coolant supply system 100 iscapable of almost instantaneous adjustment of the temperature and flowrate of the liquid coolant. In addition, sensor control unit 102preferably receives electrical signals and data from microwave source38, urethral thermometry unit 39 and a rectal thermometry unit (notshown) to further regulate the temperature and flow rate of the liquidcoolant supplied by liquid coolant supply system 102 and beingcirculated through catheter 28.

Once treatment of the BPH by thermal therapy has been completed, sensorcontrol unit 102 may be readied for treatment of another patient bysimply opening door 32, lifting jaw 136 and sliding reservoir 110 andtemperature interface module 104 off of registered pins 122 and 126,respectively, to remove the used liquid containment unit 100 fordisposal or cleaning. A pre-cleaned fresh liquid containment unit 100may be likewise simply mounted to sensor control unit 102 and suppliedwith liquid coolant for treatment of another patient.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A coolant-sensor interface module for enablingtemperature and pressure of a liquid coolant within a thermal therapycatheter fluid supply system to be sensed by a temperature sensor and apressure sensor without direct contact of the liquid coolant with thetemperature sensor and the pressure sensor, the module comprising:a bodyhaving a fluid chamber with an inlet port and an outlet port forallowing the liquid coolant to circulate through the fluid chamber; atemperature interface supported adjacent the fluid chamber within thebody, wherein the temperature interface communicates a temperatureindicant of the liquid coolant circulating through the fluid chamber tothe temperature sensor which is external to the body and not in directcontact with the liquid coolant; and a pressure interface supportedadjacent the fluid chamber within the body, wherein the pressureinterface communicates a pressure indicant of the liquid coolantcirculating through the fluid chamber to the pressure sensor which isexternal to the body and not in direct contact with the liquid coolant.2. The module of claim 1 wherein the temperature interface includes:aradiation emitter adjacent the fluid chamber for emitting radiationcorresponding to the temperature of the liquid coolant circulatingthrough the fluid chamber.
 3. The module of claim 1 wherein the pressureinterface includes:a flexible diaphragm supported adjacent the fluidchamber, wherein the flexible diaphragm expands based upon the pressureof the liquid coolant circulating through the fluid chamber.
 4. Themodule of claim 1 including:a fill port extending through the body forpermitting liquid coolant to be supplied to the interface module; andmeans for sealing the fill port.
 5. The module of claim 1including:mounting detents for releasably mounting the temperatureinterface adjacent the temperature sensor and the pressure interfaceadjacent the pressure sensor.
 6. A liquid coolant containment unit foruse with a thermal therapy catheter, the containment unit comprising:acoolant-sensor interface module including: a body having a fluid chamberwith an inlet port and an outlet port for allowing a liquid coolant tocirculate through the fluid chamber; a temperature interface supportedadjacent the fluid chamber within the body, wherein the temperatureinterface communicates a temperature indicant of the liquid coolantcirculating through the fluid chamber to a temperature sensor; and apressure interface supported adjacent the fluid chamber within the body,wherein the pressure interface communicates a pressure indicant of theliquid coolant circulating through the fluid chamber to a pressuresensor; and a liquid coupling assembly for fluidly connecting thecoolant-sensor interface module to input and output ports of the thermaltherapy catheter and for containing the liquid coolant as the liquidcoolant is cooled and pumped by cooling and pumping means.
 7. The moduleof claim 6 wherein the temperature interface includes:a radiationemitter adjacent the fluid chamber for emitting radiation correspondingto the temperature of the liquid coolant circulating through the fluidchamber.
 8. The module of claim 6 wherein the pressure interfaceincludes:a flexible diaphragm supported adjacent the fluid chamber,wherein the flexible diaphragm expands based upon the pressure of theliquid coolant circulating through the fluid chamber.
 9. The containmentunit of claim 6 wherein the liquid coupling assembly includes a sealedreservoir including an inlet port and an outlet port, wherein thereservoir directs liquid flow adjacent the cooling means.
 10. Thecontainment unit of claim 9 wherein the sealed reservoir includesmounting detents for releasably supporting the sealed reservoir adjacentthe cooling means.
 11. The containment unit of claim 9 wherein thesealed reservoir comprises a thin thermally conducting bag.
 12. Thecontainment unit of claim 9 wherein the reservoir includes a pluralityof winding channels for channeling liquid flow adjacent the coolingmeans.
 13. The containment unit of claim 9 wherein the sealed reservoirincludes:a gas permeable membrane for permitting gas to escape from thesealed reservoir while preventing liquid coolant from escaping from thesealed reservoir.
 14. The containment unit of claim 6 wherein the liquidcoupling assembly includes:a pump interface for containing and isolatingthe liquid coolant from the pumping means and for communicating pressurefrom the pumping means to the liquid coolant to circulate the liquidcoolant.
 15. A liquid coolant supply system for supplying a liquidcoolant to a thermal therapy catheter, the system comprising:a sensorcontrol unit including:a pump; a cooling device; a temperature sensor;and a pressure sensor; and a liquid coolant containment unit including:acoolant-sensor interface module including:a body having a fluid chamberwith an inlet port and an outlet port for allowing the liquid coolant tocirculate through the fluid chamber; a temperature interface supportedadjacent the fluid chamber within the body, wherein the temperatureinterface communicates a temperature indicant of the liquid coolantcirculating through the fluid chamber to the temperature sensor; and apressure interface supported adjacent the fluid chamber within the body,wherein the pressure interface communicates a pressure indicant of theliquid coolant circulating through the fluid chamber to the pressuresensor; fluid coupling means for fluidly connecting the sensor interfacemodule to inlet and outlet ports of the thermal therapy catheter; andmeans for removably supporting the fluid coupling means adjacent thecooling device and the pump, the temperature interface adjacent thetemperature sensor and the pressure interface adjacent the pressuresensor so that the liquid coolant containment unit may be replaced withanother liquid cooling containment unit.
 16. The supply system of claim14 wherein the temperature interface comprises a radiation emitter whichemits radiation corresponding to a temperature of the liquid coolant andwherein the temperature sensor comprises an infrared radiation sensor.17. The supply system of claim 14 wherein the pressure interfacecomprises a flexible diaphragm which expands based upon the pressure ofthe liquid coolant circulating through the sensor interface module. 18.The supply system of claim 14 wherein the fluid coupling means includesa flexible compressible fluid conduit and wherein the pump comprises aperistaltic pump which dynamically compresses the fluid conduit to pumpthe liquid coolant through the fluid conduit to circulate the liquidcoolant.
 19. The supply system of claim 14 including:means forcontrolling the cooling device based upon temperature sensed by thetemperature sensor; and means for controlling the pump based uponpressure sensed by the pressure sensor.
 20. A liquid coolant supplysystem for supplying a liquid coolant to a thermal therapy catheter, thesystem comprising:a sensor control unit including:a temperature sensor;a pressure sensor; a peristaltic pump, wherein the pump pumps thecoolant at a rate based upon sensed pressure signals from the pressuresensor; and a cooling plate, wherein the cooling plate has a temperaturewhich varies based upon sensed signals from the infrared sensor; andliquid coolant containment unit including:a liquid reservoir configuredfor being removably supported adjacent the cooling plate, wherein thereservoir contains and channels the liquid coolant adjacent the coolingplate to cool the liquid coolant; a coolant-sensor interface moduleincluding:a body having a fluid chamber with an inlet port and an outletport for allowing the liquid coolant to circulate through the fluidchamber; a temperature interface supported adjacent the fluid chamberwithin the body, wherein the temperature interface communicates atemperature indicant of the liquid coolant circulating through the fluidchamber to the temperature sensor; a pressure interface supportedadjacent the fluid chamber within the body, wherein the pressureinterface communicates a pressure indicant of the liquid coolantcirculating through the fluid chamber to the pressure sensor; acompressible tube in fluid connection with the reservoir and the sensorinterface module, the flexible tube configured for being positionedadjacent the pump so that actuation of the pump pumps and circulates theliquid coolant through the liquid coolant containment unit; and a liquidcoupling assembly for fluidly connecting the liquid reservoir, thecoolant-sensor interface module and the compressible tube to input andoutput ports of the thermal therapy catheter.